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CHEMISTRY AND PERFORMANCE OF DIFFERENT
LIGNOSULFONATES
K. Reknes*, Borregaard LignoTech R&D, Norway
28thConference on OUR WORLD IN CONCRETE & STRUCTURES: 28 - 29 August 2003,Singapore
Article Online Id: 100028049
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8/11/2019 CHEMISTRY AND PERFORMANCE OF DIFFERENT LIGNOSULFONATES
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28
th
Conference on
OUR WORLD
IN CONCRETE STRUCTURES: 28 - 29 August 2003,
Singapore
CHEMISTRY AND PERFORMANCE OF DIFFERENT
L GNOSULFONATES
K. Reknes*, Borregaard LignoTech R D, Norway
Abstract
Lignosulphonate from different sources is being used in concrete admixture
formulations in Asia. The properties o the different lignosulphonate can vary, as the
lignosulphonate are different both
in
chemistry
and
in performance in the concrete.
Lignosulphonate produced in China, Norway
and
South Africa were compared in an
investigation including chemical analysis and concrete performance testing. The
purpose of
the
investigation was to correlate some of the differences in chemical
composition, with the concrete performance of the materials.
There are performance differences between the samples investigated. The molecular
weight is the highest for Borresperse CA and the lowest for the Chinese samples. All
the three Chinese samples have the same molecular weight distribution. The
Chinese samples are Mg lignosulphonate and the Borresperse samples are Ca
lignosulphonate. The Chinese I sample contain a high amount of insoluble. The air
entrainment is the lowest with Borresperse CA-SA and the highest with the Chinese
samples. The air entrainment affects the compressive strength. The compressive
strength is lower with the admixture samples entraining the most air than with the
admixture
samples entraining the least air. The Chinese samples contain chloride in
high concentration and are thus not suitable for formulation of concrete admixtures.
Keywords: lignosulphonate, concrete, water reducing admixture
Introduction
Lignosulfonate has been used in chemical admixture for concrete since the 1930-ties. The probably
most important single group of materials used
in
chemical admixture for concrete was
and
still is
lignosulfonate. The way lignosulfonate is being modified and altered has changed since the beginning
in the 1930-ties. During the
20
t
century, a wide range of new materials found their way into the
formulations of chemical admixture for concrete. The
use
of gluconate started
in
the 1940-ties. PNS
(naphthalene sulfonate) were developed
and
introduced in the early 1970-ties. Melamine sulfonate
(MS) were introduced around 1980, poly vinyl copolymers (VC) around 1990 and the poly carboxylic
copolymer PC) around 2000.
As
new materials have been added to the range o raw materials, new
formulations have been developed with combinations of these materials and lignosulfonate.
Lignosulphonate from different sources is being used in concrete admixture formulations in Asia.
The properties of the different lignosulphonate can vary, as the lignosulphonate are different both in
chemistry
and in
performance
in
the concrete. Difference
in
chemical composition can have big impact
on the performance o the lignosulfonate in concrete 11
2/.
These differences can be overcome by
different ways of modifying the lignosulfonate to results
in
the same performance in the concrete.
These differences do also have impact on the formulation of the concrete admixture. Lignosulphonate
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produced in China, Europe and South Africa were compared in an investigation including chemical
analysis and concrete performance testing. The purpose of the investigation was to correlate some of
the differences in chemical composition, with the concrete performance
of
the materials. The results of
the investigation are reported here.
2 Experimental
2 1 Samples
The samples used in the experimental work are described in Table 1. The three Chinese samples
were provided from Korea. The origin is not known to us. They are expected to be sodium
lignosulphonate. Borresperse CA-SA is a hardwood lignosulphonate. Borresperse CA is a softwood
lignosulphonate.
2.2 Concrete test ing
The samples were tested on performance in concrete. concrete mix proportion is
~ e s i g ~ e d
according to the European standard EN
480-1
and is shown
In
Table
2.
The aggregate particle size
distribution is composed according to the European standard EN 480-1.
8mm
8 11 mm
1116mm
Admixture
The following concrete properties were determined:
slump: initial and after
15
minutes and 30 minutes when possible,
air content and fresh density,
set time
by
measurement
of
the temperature increase in isolated box and
compressive strength and density after
24
h, 7 days and 28 days.
3 Results and discussion
The results of the chemical analysis conducted are shown in Table 3. The molecular weight of the
Chinese Iignosulphonate samples is low, and lower than that of Borresperse CA-SA. The molecular
weight distribution
of
the samples is shown in Figure
1
The weight average molecular weight (Mn) of
the Chinese and the Borresperse CA-SA is the same, but there is difference in the weight average
molecular weight (Mw). The molecular weight of Borresperse CA is much higher that that of the other
samples. This is valid for both Mn and Mw.
The amount of reducing sugar is slightly different in the samples. The Borresperse CA-SA
sample contains 2.0 reducing sugar, while the other samples contain 5-6 reducing sugar. The
total sugar content of the samples is low, as the term reducing sugar also includes other reducing
components than only sugar, i.e. reducing sugar
is
equal to reducing matter. The content of reducing
I sbwc = solids by weight of cement
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Chinese sample I is 2-3 higher than that with the other samples,
in
spite of the 0.8 dosage of
defoaming agent.
The initial set time is the same for the samples of Borresperse CA, Borresperse CA-SA,
Chinese H and Chinese A up to the dosage of 0.40 sbwc. The initial set time with the Chinese I
sample
is
higher than with the other samples at the 0.40 sbwc dosage. All the Chinese samples
have approximately the same initial set time at the 0.60 sbwc dosage. The two Borresperse
samples have much longer set time than the Chinese samples at the 0.60 sbwc dosage. The
accuracy of the test method is approximately 0.5 hours.
A principle component analysis (PCA, mUltivariate data analysis) was conducted on the
concrete performance data from the data set with 0.8 TBP. The PC1 and PC2, that are explaining
91 PC1 64 and PC2 27 ) of the variation of the data, are shown
in
Figure 4. Slump (Slump_O)
and initial set time (Set) correlates with the dosage (DOS) of the admixture. This
is
as expected. The
air entrainment (Air) correlates with the admixture dosage
on
PC1, but
is
negatively correlated
on
PC2. This can be explained by the increase in air entrainment with increasing dosage (PC1). Increase
in
workability (slump) makes it easier for the entrained air to escape from the concrete. Increasing
workability
is
a result of increase
in
admixture dosage resulting in the negative correlation between air
entrainment and admixture dosage on PC2. The positive correlation between air content and slump
on PC1 implies that increased air entrainment also improves the workability of the concrete. Air
content
is
negatively correlated to the density of the fresh concrete (Dens-f) on both PC1 and PC2.
This
is
as expected: Increasing air content results
in
lower density. Density and compressive strength
are positively correlated on
PC1
both at 24 hours (C24,
024
and at 7 days (C7, 07). The 24 hour
compressive strength is negatively correlated to the density
on
PC2. The 24 hours compressive
strength
is
negatively correlated to set time on both PC1 and PC2. Increasing set time results
in
reduced 24 hours compressive strength, as expected.
-
::I
o
E
Chinese
t
hinese
Chinese
/ Borresperse CA
Borresperse CA-SA
Molecular weight
Figure 1 Molecular weight distribution for all samples used in the investigation
The normal probability plot
of
the air content
of
the fresh concrete
is
shown
in
Figure 5 and of
the initial set time in Figure 6. Some of the samples are not following the normal distribution fully. The
scores and correlation loadings from the PCA are shown in Figure 7. The scores plot show that the
Chinese I sample is grouping differently from the other samples. The other samples are grouping very
similar to each other indicating that they are not very different.
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Control
22 9 0 5 53 7
1,0
68 2
O,7
2426
11
2443 9 2440
5
The compressive strength development at the different dosages used
is
shown in Figure 8 and Figure
10. The main factors affecting the compressive strength are
s
follows:
initial set time affects the 24 hours compressive strength and
air content affects the 7 days and 28 days compressive strength.
The 24 hours compressive strength is reduced with increasing set time (Figure 9). The
compressive strength at 7 days is mainly affected by the air entrainment. Increasing air entrainment
reduces the compressive strength.
The concrete performance was also determined without addition o defoaming agent (TBP). The
data
o
this data set
is
shown
in
Figure 11. The air entrainment
o
the Chinese samples
is
higher than
that
o the Borresperse samples. Borresperse CA-SA has a much lower air entrainment than the other
samples. The need for defoaming agent needed to control the air entrainment is thus the lowest with
this material.
The difference between the set time with the different samples is
in the data set without defoaming
agent reduced relative to the data-set with 0.8 TBP, The initial slump is lower with the Chinese
samples than with the Borresperse samples.
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200r--------------------------------,
2 0 0 - - - - - - - - - - - - - - - - - - t , - - - ~ ~ ~ - - _ 1
E 5 0 - - - - - - - - - - - - - ~ - - ~ ~ ~ ~ ~ ~ - - ~
..
Q.
1 0 0 - - - - - - - - . ~ ~ ~ ~ - - - - - - - - - - - - - - _ 1
iii
0 0 ~ ~ ~ ~ ~ ~ - - - - - - - - - - - - - - - - - - - - _ 1
O - - - ~ - - ~ - - - - ~ - - ~ - - ~ - - ~ - - ~
0 00 0 10 0 20 0 30 0 40 0 50 0 60 0 70
Dosage rio sbwc)
30 0
-,----------------------------------,
25 0 --------------------------/------\
~ 20 0 t - - - - - - - - - - - - - : : : : t===----1
c.
i
15 0
+----------------; ;"-, .-: i is; ; , . . .-e ' - ' -----------\
I/) 10 0
+ - - - - - - - - - - : : l ~ ; : : i : ; ; : ; . . = = - - - - - - - - - - - - - - - - - - - \
5 0 . ,= - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -1
0 0
- - - ~ - - _ _ _ _ , - - - - _ , _ - - _ _
- - - .__- -_ ,_- - - -
5 0
4,5
4 0
~ 3 5
"0
~
3 0
... 2 5
c
8 2 0
C
1 5
1 0
0 5
0 0
0 00 0 10 0 20 0 30 0 40 0 00 0 60 0 70
Dosage rio sbwc)
T
r
../
J..
~ - - -
-l
-
F
: : :
-
--
-- . - , " " . ~
0 00 0 10
0,20
0 30
0 40
0 50 0 60
0 70
Dosage rio sbwc)
Borresperse CA
_ _ _ _ Borresperse CA-SA
- - t - - -
Chinese Sample I
--* --
Chinese Sample H
-
-lI(
-
Chinese Sample A
Borresperse CA
_ _ _ _ Borresperse CA-SA
- - t - - -
Chinese Sample I
-. * . -
Chinese Sample H
- -lI( - Chinese Sample A
Borresperse CA
_ _ _ _
Borresperse CA-SA
- - t - - -
Chinese Sample I
. -* . -
Chinese Sample H
- -lI( - Chinese Sample A
Figure
2
he concrete performance as function o dosage for all samples with 0,8 defoaming agent
TBP).
he
slump is shown at the top. The set time is shown
in
the middle and the air content
o the
fresh concrete is shown at the bottom.
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96.88
> : SA
90.63
84.38
78.13
71.88
65.63
59.38
53.13
46.88
40.63
34.38
28.13
-' .
21.88
..,.
,
15.63
9.38
3.13
-
5
10
15
20
25
30
Figure
6
Normal probability plot
of
set time
of
concrete with 0.8 defoaming agent (TBP).
PC
.
.
.
RESULT2.X.eJIi
64 1,,2PJ.
Scores
.
peA
1 2 ...
X-ex lained:
64
.
27
orrelation Loadin
1 0
PCZ
5
10
Fef
10
RESU.T2.
X-flJ;lt 64 1t..21 1.
0 5
Figure
7
Scores and loadings calculated for the concrete performance data
of
the concrete with 0.8
defoaming agent (TBP). Outliers are eliminated from the data set.
iii'
D-
i
c
e
i
ci
E
8
Figure
8
The compressive strength of the concrete with 0.8 defoaming agent (TBP).
447
P f
10
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25,0 -.-----------------
20,0 - I - - - - - - I ~ - : : - - - - - - - - - - I
.
::
g 15,0 - I - - - - - - - - ~ ~ ~ - - - - - - - l
1:
"
10,0 - I - - - - - - ~ ~ i 1 i _ - - - - - - l
8
.c
5 0
+ - - - - - - - - - - ~ ~ ~ - - - - - 1
0,0
~ - . . . . , . . . . - _ _ _ . _ - - r _ _ - . . . . _ - _ _ , _ ~ H
0,0 5,0 10,0 15,0 20,0 25,0 30,0
Set time [h]
- + - - Borresperse CA
Borresperse CA-SA
Chinese Sample I
- - -x - -
Chinese Sample H
- * - Chinese Sample A
Figure 9
The
24 hours compressive strength as function o the set time for the concrete with 0.8
TBP
Conclusion
There are chemical differences and performance differences between the samples investigated,
The molecular weight
is
the highest for Borresperse CA and the lowest for the Chinese
samples. All the three Chinese samples have
the same
molecular weight distribution. The Chinese
samples are Mg lignosulphonate
and
the Borresperse samples are
Ca
lignosulphonate. The Chinese I
sample contain a high amount of insoluble.
The air entrainment is the lowest with Borresperse CA-SA and the highest with the Chinese
samples, The air entrainment affects the compressive strength. The compressive strength is lower
with
the
admixture samples entraining the most air than with
the
admixture samples entraining the
least air
The Chinese samples contain chloride
in
high concentration. Chloride can be harm full
in
reinforced concrete and these lignosulfonates are thus not suitable for formulation of concrete
admixtures.
5 Reference
Gustafsson,
J.
and Reknes,
K.
Adsorption
and
dispersing properties of lignosulfonate
in
model
suspensions and cement pastes, Proceedings of the Sixth CAN M ET/AC I International
Conference on Superplasticizers
and
Other Chemical Admixtures in Concrete, Nice, October,
2000
/2/ Reknes,
K.
and Gustafsson,
J.
Effect of modifications oflignosulfonate
on
adsorption
on
cement
and fresh concrete properties, Proceedings ofthe Sixth CANMET/ACI International Conference
on Superplasticizers and Other Chemical Admixtures in Concrete, Nice, October, 2000
448
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0.20 sbwc
80,0
70,0
f
60,0
::5
50,0
tj,
~ ' ; ~
~ . - .
I
;
40,0
Q.
30,0
1
E
c 20,0
IJ
10,0
0,0
0
0.40 sbwc
90,0
80,0
ii
70,0
Q..
i
60,0
. :
i
50,0
1: 40,0
II
~ 30,0
c 20,0
10,0
0,0
0
0.60 sbwc
80,0
70,0
f
60,0
::5
50,0
tj,
; 40,0
7 14 21
28
Time [days]
7 14
21 28
Time [days]
=:;::t
~ - - -
.
:,.:.:..- -:..::-+
. : : . . ; -
~ :
/ /
II
.
30,0
20,0
10,0
0,0
.J
o
7
14 21 28
Time [days]
5
5
35
_ _ _ _ Borresperse CA
Borresperse CASA
-+ - -Ch inese
Sample I
..
*
..
Chinese Sample H
-
*
-
Chinese Sample A
----
Borresperse CA
Borresperse CA-5A
- --
Chinese Sample I
Chinese Sample H
-
*
-
Chinese Sample A
_ _ _ _
Borresperse CA
Borresperse CASA
- --
Chinese Sample I
..
* ..Chinese Sample H
-
*
- Chinese Sample A
Figure 10 The compressive strength as function of ime for the concrete with 0.8 defoaming agent
TBP).
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250
200
E 150
.E.
co
E
100
iii
50
a
0 00
30 0
25 0
_ 20 0
=.
15 0
' ;
II
10 0
5 0
0 0
0 00
10 0
9 0
8 0
0
7 0
a
6 0
5 0
0
4 0
3 0
2 0
1 0
0 0
0 00
0 10
0 20
0 30
0 40 0 50 0 60
0 70
Dosage
r o
sbwc)
0 10 0 20 0 30 0 40 0 50
0 60 0 70
Dosage
[ sbwc
0 10 0 20 0 30 0 40 0 50 0 60 0 70
Dosage r o
sbwc)
- - + -
Borresperse CA
_ _ _ _ Borresperse CA-SA
- --- Chinese Sample I
- - .)